Composite lightening material for well cementing and its preparation method, deep well composite cement slurry and its application

Abstract

The invention discloses a composite lightening material which comprises the following components in parts by weight: 100 parts of coal ash, 10-15 parts of expanding materials and 5-10 parts of toughening materials, wherein the particle size range of the coal ash is 5-10 microns. The invention also relates to a preparation method of the composite lightening material, and the preparation method comprises the following steps: i) carrying out smashing and ball milling on the coal ash through an overhang roll mill, classifying the smashed and ball-milled coal ash through a classifier, and collecting the coal ash with the particle size range of 5-10 microns after the classification to obtain modified coal ash; and ii) mixing the modified coal ash obtained in the step i) with the expanding materials and the toughening materials according to the proportion so as to obtain the composite lightening material. Meanwhile, the invention also discloses deep well composite cement paste and an application of the composite cement paste in well cementing of oil / gas wells.

Description

technical field [0001] The present invention relates to the field of petroleum exploration and development, in particular to a composite lightening material for well cementing and its preparation method, deep well composite cement slurry and its application. Lighten the material. Background technique [0002] At present, during the increase and development of oilfields, due to the deep burial of some oilfield reservoirs, most of the well depths are above 6500m, the geological conditions are complex and changeable, and there are generally low-pressure and easy-to-leakage layers, which bring great difficulties and challenges to cementing operations. . The biggest difficulty in the cementing process is that leakage occurs during cementing, which leads to the return of cement slurry that does not meet the design requirements, so that the cementing quality is difficult to guarantee. Therefore, it is necessary to use a low-density cement slurry system during cementing to reduce ...

AI Technical Summary

Problems solved by technology

But conventional fly ash can only reduce the density of cement slurry to 1.60g / cm 3 around, and poor stability

[0004] 200710120029.3 "Low Temperature and Low Density Cement Slurry" introduces the formula of a low density cement slurry, but does not give the specific composition of the lightening agent and the production method of the lightening agent

However, its modification is air separation and classification of fly ash and chemical modification of surface spraying, which is mainly used as filling material for rubber products and is not suitable for use in oil and gas wells.

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